Light-emitting diodes (LEDs) are used as semiconductor light sources. Because of various advantages such as high brightness, long product life, small footprint and low power consumption, LEDs are considered to be the choice of the illumination devices of the next generation. A goal for research and development in the LED field is to improve the luminous efficacies of the LEDs and epitaxial wafers for manufacturing LED chips.
Some LED chips include a semiconductor material of aluminum gallium indium phosphide (AlGaInP) grown by heteroepitaxy to form a quantum well structure for emitting light. The AlGaInP-based LED chips can be installed using a flip chip technology. However, due to the height differences of the P and N electrodes of the LED chips, the bonding quality through the flip chip process needs an improvement. Furthermore, the AlGaInP-based LED flip-chips are prone to electrical leakage.